A large sinkhole opened up in the early morning on August 22, 2004, in Sterling Heights, Michigan, on 15 Mile Road. The sinkhole, estimated to be 30 feet deep, 60 feet wide, and 160 feet long, was caused by a break in an 11-foot-diameter sewer interceptor. The sewer line, which is more than 40 feet below ground, was installed in the late 1960s; problems with soil and sand conditions were encountered at the time. Sewer officials reported that another collapse occurred in 1978 about 2000 feet to the east, releasing millions of gallons of raw sewage; Macomb County is still paying the $25 million repair bill. Officials do not think the two collapses are related.
Staff from the Detroit Water & Sewerage Department are at work creating a temporary bypass to carry the 30 to 60 million gallons a day of untreated sewage that the broken pipe normally conveys to a treatment plant. About 7 million gallons of sewage will be diverted to the Mount Clemens plant for treatment. George Ellenwood, a spokesman for the department, said crews will begin stabilizing the site by driving steel plates and pumping cement to shore up the ground.
The temporary line could take weeks to construct, and complete repairs may continue into next summer. The broken line is currently being kept open by a high-powered jet water system. “It is not totally collapsed or blocked off,” deputy Macomb Public Works commissioner said. “We will be able to maintain service to customers in Macomb County.”
Some houses nearby were temporarily evacuated, and a telephone cable was damaged, disrupting service to 350 customers.
Source: Click on Detroit